Difference between revisions of "Team:KU Leuven/Protocols"
ImkeEnsinck (Talk | contribs) |
|||
| Line 68: | Line 68: | ||
#grad { | #grad { | ||
| − | background: -webkit-linear-gradient(#C17952,#ffd4a6,#edf2f4); /* Safari 5.1-6.0 */ | + | background: -webkit-linear-gradient(#C17952,#ffd4a6,#edf2f4, ,#edf2f4); /* Safari 5.1-6.0 */ |
| − | background: -o-linear-gradient(#C17952,#ffd4a6,#edf2f4); /* Opera 11.1-12.0 */ | + | background: -o-linear-gradient(#C17952,#ffd4a6,#edf2f4,#edf2f4); /* Opera 11.1-12.0 */ |
| − | background: -moz-linear-gradient(#C17952,#ffd4a6,#edf2f4); /* Firefox 3.6-15 */ | + | background: -moz-linear-gradient(#C17952,#ffd4a6,#edf2f4,#edf2f4); /* Firefox 3.6-15 */ |
| − | background: linear-gradient(#C17952,#ffd4a6,#edf2f4); /* Standard syntax */ | + | background: linear-gradient(#C17952,#ffd4a6,#edf2f4,#edf2f4); /* Standard syntax */ |
} | } | ||
| Line 343: | Line 343: | ||
<li>When trying to measure an oscillation in the cell membrane with patch-clamp, you cannot use voltage-clamp, since this technique doesn't allow the cell to change its membrane potential. We used current-clamp instead. Here, you can inject a pre-defined current into the cell which allows you to see how the membrane potential of the cell responds to the current. When a cell oscillates by itself, the membrane potential will oscillate while injecting 0 current. However, we often needed to inject a small negative current (-300pA) into a cell to elicit an oscillation in a cell with an extracellular Krebs solution.</li> | <li>When trying to measure an oscillation in the cell membrane with patch-clamp, you cannot use voltage-clamp, since this technique doesn't allow the cell to change its membrane potential. We used current-clamp instead. Here, you can inject a pre-defined current into the cell which allows you to see how the membrane potential of the cell responds to the current. When a cell oscillates by itself, the membrane potential will oscillate while injecting 0 current. However, we often needed to inject a small negative current (-300pA) into a cell to elicit an oscillation in a cell with an extracellular Krebs solution.</li> | ||
</ul> | </ul> | ||
| + | <br> | ||
</div> | </div> | ||
| + | </div> | ||
| + | |||
<br> | <br> | ||
<div class="experiment"> | <div class="experiment"> | ||
| Line 698: | Line 701: | ||
}); | }); | ||
</script> | </script> | ||
| − | + | </br></br></br> | |
</html> | </html> | ||
{{KU_Leuven_footer}} | {{KU_Leuven_footer}} | ||
Revision as of 16:23, 25 October 2017
Protocols
In the lab, we used different experimental procedures. There are protocols for the wet and bacterial lab, for the cell culture lab and for the electrophysiology lab.
Cell Culture
Medium of HEK 293 cells
Medium contents
- DMEM (Gibco N° 41965-039) 500 ml
- 50 ml (10 %) FCS = (Hyclone)
- 10 ml Penicillin/Streptomycin (Gibco N° 15070-071) = 100-100U/ml
- 10 ml Glutamax (Gibco N° 35050-038) = 10 mM
- 5 ml Non-Essential-Amino-Acids (Gibco N° 1140-035) = 10x
Growing conditions
- Incubate at 37°C and 10% CO2
- Split cells around 70-90% confluency
- Change medium twice a week
Standard procedure for trypsinization
- Wash the cells with Versene (Gibco N° 15040-033, ± 2 min)
- Remove versene and add Trypsin (Gibco N° 25300-096)
- Incubate at 37°C (around 3-5 min)
- Stop the trypsinization by adding 5-10 times volume of medium
- Count cells
- Centrifuge for 5 minutes at 1200 rpm
- Aspirate supernatant and resuspend the cells in medium
- Plate cells for experiments or culture
Transfection Lipofectamine 3000
- Seed cells to be 70–90% confluent at transfection
- Dilute Lipofectamine Reagent in Opti-MEM Medium and mix well
- prepare mastermix of DNA (0,5 - 5 μg/μl) by diluting DNA in Opti-MEM Medium, then add P3000 (2 μl/μg DNA) Reagent and Mix wel
- Add diluted DNA to each tube of diluted Lipofectamine Reagent (1:1 ratio)
- Incubate for 5 minutes at room temperature
- Add DNA-lipid complex to cells
- Visualize/analyze transfected cells. Incubate cells for 2–4 days at 37°C. Then, analyze transfected cells.
- for more information: see thermofisher.com
Coating of glass coverslips (for patch-clamp or Ca2+ imaging)
Poly-L-lysine (PLL, sigma P2636)
- Dissolved at 0.1 mg/ml in Milli-Q H2O
- Stored at –20°C
- Once opened stored at RT
Coverslips (18mm)
- Prepare 12-well plates with a coverslip in each well
- Transfer 1 sterilized coverslip to each well
- Add 350 ml of PLL to each coverslip
- Incubate for 20 minutes at RT
- Aspirate and add Milli-Q H2O to each coverslip
- Incubate for 20 minutes at RT
- Aspirate H2O and store for experiments. The plates can be kept for several days at 4°C.
Seeding Cells
Seeding cells for single-cell experiments
- Spray your hands with ethanol, take the 6 well plate with cells out of the incubator and check the density of the cells
- Place the cells under the flow
- Remove the medium
- Wash the cells with 1 ml of versene for 2 minutes
- Remove versene and add 500μl of trypsin
- Incubate at 37°C, 10% CO2 for about 5-10 minutes
- Stop the trypsinization by adding 5 ml of medium.
- Transfer cell suspension to a 50 ml Falcon tube
- Separate the cells by pulling them with a 5 ml syringe through a black needle of 22G (5-10 times)
I. Ca2+ imaging
- Cells are typically seeded in a 12-well plate with PLL coated round coverslips of 18 mm
- Add 1 ml of medium to each 12-well of your plate
- If the cells in the 6-well had a density of 95-100%, typically seed 400-500 microliters of cell suspension per 12-well (density depending on experimental needs)
- Incubate at least 2 hours for cell attachment to the coverslip
II. Patch clamp
- Cells are typically seeded in a 12-well plate, on PLL coated round coverslips of 18 mm
- Add 1 ml of medium to each 12-well of your plate
- If the cells in the 6-well had a density of 95-100%, typically seed 100-300 microliters of cells per 12-well (density depending on experimental needs)
- Incubate at least 2 hours for cell attachment to the coverslip
Wet Lab
Transformation of MAX Efficiency™ DH5α™ Competent Cells
Day 1
- Add 25µL of bacteria to the bottom of a polypropylene 14mL Falcon tube (352059). Place on ice.
- Add either 0.5µL of 100ng/µL plasmid or 1 to 5µL of a ligation mix to the bacteria. Mix gently by shaking. Leave on ice for 30 minutes
- Preheat the SOC medium and waterbath to 42ºC.
- Perform a heat shock. Place cells at 42ºC for 30 to 45 seconds. Return to ice for 2 minutes.
- Add 0.5mL SOC medium.
- Place in shaking incubator at 37ºC for 1 hour.
- Plate and spread on plates containing 50µg/mL of a specific antibiotic resistance markers. Incubate overnight at 37ºC for maximum 16 hours.
Day 2
- Add 3mL of LB medium containing 50µg/mL of a specific antibiotic resistance marker to a 14mL polystyrene Falcon tube (352057).
- Pick a single colony using a Inoculation loop. Transfer colony into medium and shake. In order to perform a miniprep, grow at 37ºC overnight and skip to 'Day 3'. Otherwise, grow for 3 to 4 hours and continue.
- Add 70mL LB medium containing 50µg/mL of a specific antibiotic resistance marker to a sterile erlenmeyer.
- Add the bacteria to the new medium: ½ of the medium in the Falcon if the growth is visible, all of the medium if the solution is still clear.
- Place erlenmeyers in shaking incubator at 37ºC overnight or for maximum 16 hours.
Day 3
- Harvest plasmids using mini-, midi- or maxiprep kit.
PCR
Reaction mixture
| Product | Final concentration | Volume for 50µL reaction |
|---|---|---|
| 5x Phusion buffer HF | 1x | 10µL |
| dNTPs (10mM) | 200µM each | 1µL |
| Forward primer (25µM) | 0.5µM | 1µL |
| Reverse primer (25µM) | 0.5µM | 1µL |
| Template DNA | 1µL | |
| Phusion DNA polymerase | 0.02U/µL | 0.5µL |
| Milli-Q Water | 35.5µL |
Protocol
| Step | Time | Temperature | Number of cycles |
| Initial denaturation | 30’’ | 98ºC | 1 |
| Denaturation | 10’’ | 98ºC | 30 |
| Annealing | 30’’ | *ºC (*: 2 degrees below Tm) | |
| Extension | 3’30’’ | 72ºC | |
| Final extension | 7’ | 72ºC | 1 |
| End | - | 4ºC |
Patch Clamp
Methods
- We used whole-cell patch clamp to measure the membrane voltage and ion currents across a HEK cell membrane. To measure whole-cell, we pushed a glass pipette against the membrane of a cell, to seal the membrane completely against the membrane. Afterwards, we caused a sudden negative pressure in the glass pipette, which destroys the membrane in the opening of the glass pipette. The solution within the pipette will subsequentially mix with the intracellular compartment of the cell, which allows us to measure with a pre-defined intracellular buffer.
Voltage clamp
- To study the currents through different ion channels with whole-cell patch clamp, we used a specific technique called "Voltage clamp". Here, we maintain a pre-defined membrane potential to study the activation of α1G, HCN2 and hERG. Each of these ion channels has a specific way of activation, which can be quantified using voltage clamp. When clamping the voltage at a certain value, a cell will adapt to the voltage by increasing or decreasing ion currents. These currents will be measured using this technique
Current clamp
- When trying to measure an oscillation in the cell membrane with patch-clamp, you cannot use voltage-clamp, since this technique doesn't allow the cell to change its membrane potential. We used current-clamp instead. Here, you can inject a pre-defined current into the cell which allows you to see how the membrane potential of the cell responds to the current. When a cell oscillates by itself, the membrane potential will oscillate while injecting 0 current. However, we often needed to inject a small negative current (-300pA) into a cell to elicit an oscillation in a cell with an extracellular Krebs solution.
Calcium imaging
- Calcium imaging is a scientific technique which can be used to measure and follow the calcium ions inside and/or outside the cell. We used a specific dye (Fura2-AM) to follow the calcium ions by the rate of fluorescence. For our project, we only used the calcium imaging for testing whether there were oscillations or not and what potassium concentrations (in a krebs buffer) were needed. We did not mathematically analyse the data we received. We only used it as a criteria for the patch clamp.
Preparation of imaging
Fura-2, AM (MW: 1001,9)
- Dilute 50 μg of Fura-2 in 50 μl DMSO (1 mM stock solution)
- Make aliquots of 2 μl in brown eppies and store at -20°C
- To load cells (1 well): add 2 μl of Fura-2 to 1 ml of medium (2μM work solution)
- Incubate cells for 30 minutes before measurement
Intra- and extracellular buffers
Buffers for stable HEK-HCN cells
| External Solution | MW (g/mol) | mM | g/l |
|---|---|---|---|
| NaCl | 58,44 | 150 | 8,766 |
| KCl | 74,56 | 10 | 0,7456 |
| CaCl2 x 2H2O | 147,02 | 3 | 0,44106 |
| MgCl2 x 6H2O | 203,3 | 1 | 0,2033 |
| Hepes | 238,31 | 10 | 2,3831 |
| pH 7.4 NaOH |
| Pipetsolution | MW (g/mol) | mM | g/100 ml |
|---|---|---|---|
| KCl | 74,56 | 150 | 1,1184 |
| MgCl2 x 6H2O | 203,3 | 0,5 | 0,010165 |
| Hepes | 238,31 | 10 | 0,23831 |
| EGTA | 380,35 | 1 | 0,038035 |
| pH 7.4 KOH |
| Activator HCN: 100 µM cAMP MM 329,21 g/mol | Stock 30 mM: 0,01g/ml |
| Blokker HCN: 10 mM CsCl2 MM 168,37 g/mol | Stock 1 M: 0,168 g/ml |
Buffers for transfected HEK-HCN and HEK-hERG cells
| Krebs | MW (g/mol) | mM | g/l |
|---|---|---|---|
| NaCl | 58,44 | 150 | 8,766 |
| KCl | 74,56 | 5 | 0,3728 |
| CaCl2 x 2H2O | 147,02 | 2 | 0,29404 |
| MgCl2 x 6H2O | 203,3 | 1,5 | 0,30495 |
| Hepes | 238,31 | 10 | 2,3831 |
| Glucose monohydrate | 198,17 | 10 | 1,9817 |
| pH 7.4 NaOH |
| K-Sol | MW (g/mol) | mM | g/l |
|---|---|---|---|
| NaCl | 58,44 | 0 | 0 |
| KCl | 74,56 | 155 | 11,5568 |
| CaCl2 x 2H2O | 147,02 | 2 | 0,29404 |
| MgCl2 x 6H2O | 203,3 | 1,5 | 0,30495 |
| Hepes | 238,31 | 10 | 2,3831 |
| Glucose monohydrate | 198,17 | 10 | 1,9817 |
| pH 7.4 NaOH |
- The Na+ and K+ concentration is always 155 mM and when we made another buffer with another K +-concentration, the Na + concentration changes with it. The other components remained the same. (The most useful K + concentration is between 1 and 5 mM.)
| Pipetsolution | MW (g/mol) | mM | g/100 ml |
|---|---|---|---|
| KCl | 74,56 | 150 | 1,1184 |
| Hepes | 238,31 | 10 | 0,23831 |
| MgCl2 x 6H2O | 203,3 | 0,5 | 0,010165 |
| EGTA | 380,35 | 1 | 0,038035 |
| pH 7.4 with KOH |
Buffers for TRPM3 cells
| external solution | MW (g/mol) | mM | g/100 ml |
|---|---|---|---|
| NaCl | 58,44 | 150 | 8,77 |
| MgCl2 x 6H2O | 203,3 | 1 | 0,2 |
| Hepes | 238,31 | 10 | 2,38 |
| pH 7.4 with NaOH |
| Pipet solution | MW (g/mol) | mM | g/100 ml |
|---|---|---|---|
| dl-Asp | 133,1 | 100 | 1,331 |
| CsCl | 168,36 | 45 | 0,757 |
| Hepes | 238,31 | 10 | 0,238 |
| MgCl2 x 6H2O | 203,3 | 1 | 0,0203 |
| EGTA | 380,35 | 10 | 0,38 |
| pH 7.4 with CsOH |
